Sewing machines



y 1962 J. A. WENNSTROM 3,034,460

SEWING MACHINES Filed om. 20, 1960 I 4 Sheets-Sheet 1 Fig. 1 INVENTOR.

J0/m 14. Wennsfrom A TTORNEY May 15, 1962 J. A. WENNSTROM SEWINGMACHINES 4 Sheets-Sheet 2 Filed Oct. 20, 1960 INVENTOR.

John A Wenn sfram ATTORNEY y 1 1962 J. A. WENNSTROM 3,034,460

SEWING MACHINES Filed Oct. 20, 1960 4 Sheets-Sheet 3 INVENTOR. John A.Wennsfrom 1w. TTORNfY United States Patent York Filed Get. 20, 1960,Ser. No. 63,787 Claims. (Cl. 112-123) Industrial sewing machinesdesigned to perform a variety of sewing operations, such as overseaming,hemming and overedging, are generally equipped with a trimming cutterwhich trims the edge of the material immediately before the seam isformed. The trimming cutter commonly consists of a stationary lowercutter blade adjacent the needle plate and a movable upper cutter bladewhich is generally downwardly slanted towards the needle plate and isoperated in timed relationship with the feeder.

I Economy requires that the width of the trimmed oil strip be held to aminimum.

Experience has shown that this requirement is difficult to meet incertain sewing operations and with certain materials.

In hemming knit goods, tricot, nylon materials and elastic materialswhich have a tendency to roll or curl, particular difi'iculties areencountered.

Three thicknesses of material pass under the presser foot in a hemmingoperation in which the material is folded in the shape of an S as viewedfrom the end, and in which the machine trims the top layer of thematerial and forms a seam between the trimmed edge and the foldtherebelow.

Quality of workmanship demands that this seam is continuous. In thepast, however, difficulties were experienced in crossing seams. Theneedle failed to catch the lower fold at, or immediately following, thecrossed seams resulting in a faulty open hem at that point. Openings inthe seam of the order of one-half inch were common and these openingsassumed even larger dimensions when the garment was subsequentlystretched. A difiiculty of a different character is encountered incertain sewing operations, for example hemming, of elastic materialwhich has a tendency to roll or curl back into the seam. The danger ofcurling into the seam is lessened if an ample overlap is provided whichis then trimmed off during the sewing operation and therefore representswaste.

The present invention overcomes both of the aforementioned difiicultieswith the same mechanical equipment, the heart of which is a roller onthe presser foot, movable up and down with the presser foot andextending into the area in front of the trimming cutters.

It has been proposed to fit the presser foot with a laterally extendingfinger. These attempts, however, proved unsuccessful, as the fingerreadily catches cross seams and frequently causes the material to rideup on the upper trimmer with resulting failure of the trimmingoperation.

Particulars of my improved construction, and the above as well asfurther objects, features and advantages of this invention will appearmore fully from the detailed description which follows accompanied bydrawings showing, for the purpose of illustration, an embodiment of thisinvention installed in an industrial sewing machine of otherwise knownconstruction. The invention also resides in certain new and originalfeatures of construction and a combination of elements hereinafter setforth and claimed.

Although the characteristic features of the invention which are believedto be novel will be particularly pointed out in the claims appendedhereto, the invention itself 3,fi34,460 Patented May 15, 1962 and themanner in which it may be carried out may be better understood byreferring to the following description taken in connection with theaccompanying drawings forming a part of it in which:

FIG. 1 is a perspective View of an industrial sewing machine in which myinvention is incorporated, the machine being set up to perform a hemmingoperation on stretchable goods;

FIG. 2 shows the machine of FIG. 1 with its presser foot swung out ofthe way to expose the needle, the looper and the trimming mechanism;

FIG. 3 is a perspective view on an enlarged scale of the presser footand surrounding elements after removal of the goods, the hem fold guidebeing swung up; and

FIG. 4 is a perspective view from above of the presser foot, the rolleron the presser foot and a guide on the needle plate.

In the following description and in the claims various details will beidentified by specific names for convenience. The names, however, areintended to be generic in their application. Corresponding referencecharacters refer to corresponding parts in the several figures of thedrawings.

The drawings accompanying, and forming part of, this specificationdisclose specific details of the invention for the purpose ofexplanation of broader aspects, but it is understood that the detailsmay be modified without departure from the principles of the inventionand that the invention may be applied to other machines than the oneshown.

Referring to FIGS. 1 and 2, the industrial sewing machine 11 is ofgenerally known construction except for certain details hereinafterdescribed and claimed at the end of the specification. The machine neednot be described in great detail with respect to its generalconstruction, particularly since a detailed description of a machine ofthis general type is found in the prior patent to R. A. Nering,2,827,869, dated March 25, 1958.

Suflice it to say that the machine is driven by a belt which may beplaced in the V-groove 12 of a hand wheel 13 on the end of a drive shaftwhich is not visible in the drawings.

The machine is set up to perform a hemming operation on knit goods whichrequire a hem stitch permitting stretching of the material lengthwise ofthe hem. Two spools of thread 14 and 15 are visible from which threads16 and 17 extend through tensioning assemblies 18 and 19 to the needle2% and the looper 21, respectively. The needle 20 is curved and travelsback and forth in the direction of its curvature and the looper 21travels roughly in a direction towards, and away from, the observer ofFIG. 1.

A presser foot arm 22 (see also FIG. 3) is pivotally mounted on the bodyof the machine at 23 so that it may be swung out of the Way as shown inFIG. 2. The presser foot arm is normally engaged by a spring urgedplunger assembly 24 comprising a lever 25 for raising the plunger proper26 out of engagement with the presser foot arm whenever it is desired toswing the presser foot out of the way. FIG. 2 shows the lever 25 in itsraised position in which the plunger 26 is withdrawn. The presser footarm 22 has a substantially horizontal pin 27 at its end resting in asurface depression of the presser foot 28 which may pivot about the pin27 and is attached to the presser foot arm by means of a hinge springplate 29 which is roughtly of the shape of the figure 6. The finger ofthe 6 bears down on the pin 27 from above and the hinge spring plate maybe loosened or tightened by means of a screw 30 extending through thebody of the 6 into the presser foot (see also FIG. 4).

The presser foot has an upwardly curved toe portion 31.

A hearing block 32 is mounted by a screw33 in a transverse recess 34just forward of the hinge spring plate 29 and carries a roller 35 withfreedom of rotation about a substantially horizontal axis. The roller 35has a small diameter portion 36 adjacent the bearing block and a largediameter portion 37 remote from the bearing block. The large diameterportion is preferably tapered, as the drawings show, and lies justforward of the upper trimmer 38 which is a blade of substantiallyL-shaped cross section, disposed at a downward slant with its lowercutting end ground substantially vertical. The trimmer 38 is clamped toan upper cutter holder 39 which moves up and down and is provided with aholder clamp 44} and screw 41 by means of which the trimmer knife istightened against the holder 39 proper. The corresponding lower trimmeris partially obscured in the drawings by other parts, but a portion maybe seen at 42 in FIG. 4, as well as a portion of the screw 43 whichsecures it next to the needle plate 44.

As disclosed in detail in the above mentioned patent to Nering2,827,869, one rotation of the main drive shaft carrying the hand wheel13 causes the needle 20 to perform one stitch, the trimmer 38 to performone cutting stroke, and the feed dog 49 to perform one feed stroke, allin timed relationship.

A stationary guide 45 secured by a mounting screw 46 is installed inadvance of the roller and alongside the toe of the presser foot, as isbest seen in FIGS. 3 and 4. The guide has a downwardly tapered trailingportion 47 which terminates just short of the roller and forms a nipwith the roller, so that goods pass above the trailing portion of theguide and underneath the roller. The width of the trailing portion isless than the lateral extent of the roller beyond the side edge of thepresser foot. For this purpose the guide is provided with a curvedlateral portion 48, as best seen in FIG. 4. FIGS. 3 and 4 also show theteeth of the feed dog 49 adjacent to the stationary teeth 50 on theneedle plate 44.

Referring particularly to FIG. 3 which illustrates the disposition ofthe roller 35 and of the stationary guide 45 with respect to the trimmer38, it is readily seen that material passing through the nip between theroller and the guide is prevented from climbing up on the upper trimmerknife so that positive trimming action is insured.

Returning now to FIGS. 1 and 2, it is seen that the material 51 is firstfolded back upon itself, as visible in part at 52, whereupon thematerial is folded again at 53 so that three layers of material areformed. The bottom layer passes over the work plate (FIG. 3), whereasthe upper two layers pass through a hem fold guide 55 so that theoperator may gauge the width of the hem more conveniently. Viewing thehem from the front, that is from the operators end, the material isfolded in the shape of an S and in such a way that the edge 56 of thematerial extends slightly beyond the first fold. The margin should beslight, of the order of one-quarter of an inch. If less, the productionof a clean hem is somewhat uncertain, if more, the operation becomeswasteful because the margin must be trimmed oif by the trimmers.

If elastic material is being sewed, the margin tends to curl up and rollinto the hem, as well as tending to ride up on the upper trimmer. Forthis reason, operators heretofore were tempted to work with an amplemargin, sometimes as much as one-half inch, resulting in excessive wasteof material. As shown in FIG. 1, however, the roller and stationaryguide prevent an upward curl of material which is quite noticeable at 57even though the material used in the illustration was not elasticmaterial, but simply knit nylon.

After the hemming operation the material is flattened out along thefirst fold 52 and has then the appearance of the hem 58.

Turning to FIG. 2, the presser foot has a flat heel portion 59 rearwardof the hinge 27, the heel portion being cut out at 60 to provide spacethrough which the needle passes. The plate 61 on the side of the presserfoot arm is a thread cutter plate (FIG. 3) which permits cutting of thethread 16, for example by pulling the thread forward into a sharp edgedwedge shape cutout 62 in the plate.

Oviously the shape of the presser foot and other elements of the machinemay be varied to suit the individual requirements of specific sewingjobs.

What is claimed is:

1. In a sewing machine, the combination of a lower feeder; a presserfoot above the feeder; a lower stationary cutter alongside the feeder;an upper cutter in shearing association with the lower cutter; a roller;and means for mounting said roller on said presser foot for rotationabout a substantially horizontal axis, the roller being in a position toextend laterally beyond the side edge of the presser foot and in frontof the cutters so as to bear down On that portion of the material to besewed which is trimmed off by the cutters.

2. In -a sewing machine, the combination of a lower feeder; a presserfoot above the feeder; a lower stationary cutter alongside the feeder;an upper cutter in shearing association with the lower cutter; a roller;and means for mounting said roller on said presser foot for rotationabout a substantially horizontal axis, the roller being in a position toextend laterally beyond the side edge of the presser foot and in frontof the cutters so as to bear down on that portion of the material to besewed which is trimmed off by the cutters, the roller having a smalldiameter portion adjacent the presser foot and a large diameter portionremote from the presser foot.

3. In a sewing machine, the combination of a lower feeder; a presserfoot above the feeder; a lower stationary cutter alongside the feeder;an upper cutter in shearing association with the lower cutter; a roller;means for mounting said roller on said presser foot for rotation about asubstantially horizontal axis, the roller extending beyond the side edgeof the presser foot nearest the cutters and lying in advance of thecutters, the roller having a portion of small diameter adjacent saidside edge and a large diameter portion at a greater distance from saidside edge; and a stationary guide in advance of the roller and alongsidethe toe of the presser foot, the guide having a downwardly taperedtrailing portion terminating at said roller, the width of said trailingportion being lms than the lateral reach of said roller.

4. In a sewing machine, the combination of a feed dog; a presser footabove said feed dog, said foot having an upwardly curved leading toeportion and a trailing heel portion, the foot being cut out to providespace through which the needle passes; means for hingedly mounting thefoot about a transverse substantially horizontal hinge axis; a rollermounted on the foot for rotation about a substantially horizontal rolleraxis in advance of, and substantially parallel to, said hinge axis, saidroller, extending beyond the left side edge of said foot and having asmall diameter portion adjacent said edge and a portion of largerdiameter at a greater distance from said edge than said small diameterportion; and a stationary guide in advance of the roller and alongsidethe toe of the presser foot, the guide having a downwardly taperedtrailing portion positioned to the side of said feed dog, said trailingportion terminating at said roller, the width of said trailing portionbeing less than th lateral extent. of the roller beyond the side edge ofthe presser foot.

5. In a sewing machine, the combination of a feed dog; a presser footabove said feed dog, said foot having an upwardly curved leading toeportion and a trailing heel portion, the foot being cut out to providespace through which the needle passes and having a transverse recess inits top surface in advance of said space; means for hingedly mountingthe foot about a transverse substantially horizontal hinge axisrearwardly of said recess; a bearing block mounted in said recess; aroller pivotally supported on said block about a substantiallyhorizontal axis to extend beyond the left side edge of the foot, theroller having a small diameter portion adjacent said 5 6 block and alarge diameter portion at a greater distance ing towards the straightside for progressively decreasing from said block than said smalldiameter portion; and a the width of the trailing portion which :at theend measures stationary guide in advance of said roller and alongsideless than the distance of the large diameter portion of the the toe ofthe presser foot, the guide having a downwardly roller from said block.tapered trailing portion terminating at said roller, said trailingportion being located laterally adjacent said 5 References cued m thefile of thls patent feed dog, said guide further having a substantiallystraight UNITED STATES PATENTS side substantially parallel to andalongside the said left 1,820,829 Ray Aug. 25, 1931 side edge of thefoot and a second opposite side converg- 2,694,066 Knaus et a1 Aug. 18,1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,034,460 May 15, 1962 John A. Wennstrom It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 3, .line 48, after "plate" insert 54 column 4, line 53, after"roller" strike out the comma.

Signed and sealed this 30th day of October 1962.

(SEAL) Attest:

ERNEST w. SWIDER ID LADD Attesting Office! Commissioner of Patents

